CSharp-Coder

Master C# collections performance: List vs Dictionary vs HashSet vs Queue with Big-O tables, real benchmarks, and code examples. Pick the right one today. Choosing the right data structure is one of the highest-leverage performance decisions you can make in .NET — and C# collections are where most of those decisions happen. Should you use a List<T> or a Dictionary<TKey, TValue> ? When does a HashSet<T> beat both? And where does Queue<T> fit in? In this guide, we'll compare the four most-used collections in C# with Big-O complexity tables, runnable benchmark code, and clear rules for when to use each. By the end, you'll be able to justify your collection choice in a code review — not just guess. Why C# Collections Performance Matters Every collection type in .NET makes a trade-off. List<T> gives you cheap indexed access and great iteration speed but slow lookups by value. Dictionary<TKey, TValue> gives you near-instant lookups...